The effects of diastolic blood pressure(DBP)on prognosis of heart failure with preserved ejec-tion fraction(HFpEF)are still not clear,probably due to the underlying heterogeneity of HFpEF.This study was aimed to evaluate the effects of DBP in patients with atrial fibrillation(AF)-induced or AF-exacerbated HFpEF,which is a clinical syndrome with high homogeneity that has seldom been discussed.Methods In this retrospec-tive cohort study,955 patients diagnosed with AF and HFpEF were screened.Patients with specific underlying cardiovascular diseases or other severe comorbidities were excluded.A total of 191 patients were included.Pa-tients were assigned to one of the two groups:DBP＜75 mmHg or DBP≥75 mmHg All-cause mortality was tak-en as primary endpoint,and all-cause re-hospitalization and HF specific re-hospitalization were measured as sec-ondary endpoints.Results The mean follow-up was 49 months.Multiple established clinical risk factors and prognostic biomarkers for heart failure were adjusted.Patients with DBP＜75 mmHg demonstrated higher all-cause mortality compared with patients with DBP of＞75 mmHg[odds ratio(OR):1.669,95％confidence Inter-val(CI):1.040-2.679,P=0.034).The risk of all-cause re-hospitalization was also increased in the group with DBP＜75 mmHg(OR:1.426,95％Cl:1.006-2.022,P=0.047).However,there was no statistically significant dif-ference in the risk of re-hospitalization due to HF between the two groups(OR:1.005,95％CI:0.565-1.787,P=0.986).Conclusions In patients with AF-induced or AF-exacerbated HFpEF,DBP＜75 mmHg was associated with higher all-cause mortality and all-cause re-hospitalization,but was not associated with re-hospitalization due to HF.